Sir Charles W. Shults III
- Jan 1, 1970
electricked said:Hello all,
I have a question about the diagram and explanation given on the following
It says that while the power supply lasts the equipment will be powered by
it and if it fails, the battery will start conducting and give power to the
Now, I understand how this works, but what troubles me is that if both are
in great operating order, why doesn't the battery conduct and the power
supply wait until the battery is dead? Is it because the power supply
provides a higher voltage? Please explain.
The explanation on the page you supplied was quite clear and concise.
If diode D2 is not forward biased, it cannot conduct. If 15 volt power is
available, D2 is reverse biased and power from the battery cannot pass
through it. Only when then 15 volts fails can D2 conduct battery power.